Just started watching Dexter. Only watched the pilot so far and it's looking good. Awesome even.
I have a guess of who is the killer, probably I'm not right, but after watching just the pilot I think it might be Dexter's boss. She obviously fancies him, and seems a bit creepy. She dismissd, his sister's idea (well it wasn't really her idea of course) about the refrigerator van straight away. So maybe it's her who wants to "play" with Dexter?
I'll watch some more tonight, so I might well adjust my guess tomorow:)